The sanctions were imposed as part of a new campaign against corruption and illegal financing initiated by the Foreign Minister.
According to British authorities, Firtash illegally earned hundreds of millions of pounds through corruption and control over gas distribution in Ukraine, as stated in the report.
It is noted that some of this money was invested in the UK real estate market, concealing tens of millions of pounds.
Also under sanctions are his wife, Lada Firtash, who owns her husband's assets in the UK, including the old Brompton Road subway station building, and financial intermediary Denis Gorbunenkо, who is alleged to have facilitated Firtash's corrupt schemes.
All three have been banned from entering the UK, and their British assets have been frozen, as highlighted in the report.